Sweden launched a preliminary investigation on Thursday to determine whether Israel acted illegally against its nationals who were involved in 2010 and 2012 flotilla efforts to break the blockade of Gaza.

A complaint alleging aggravated assault, illegal threats and theft in international waters was filed in Sweden in 2013 by the Ship to Gaza group on behalf of some 20 Swedish nationals who were either on ships that joined the Mavi Marmara in the 2010 flotilla, or another ship that set sail in 2012.

Israel arrested and deported participants in the flotillas.

Foreign Ministry spokesman Yigal Palmor said Israel had no comment on the matter.

One Israeli official stressed that the investigation was in a very preliminary stage, with the Swedish prosecutor needing to decide whether there is room for an indictment. No Israelis have been named as defendants, and the Swedes have not been in contact at all with Israel about the matter.